This invention concerns air balancing hoists in which a load supporting cable or chain is wound on a drum which is configured as a spool fixed to a ball nut received on a ball screw. The spool is axially engaged with a piston controllably subjected to air pressure to be axially advanced on the ball screw. This causes the spool to be rotatably held, advanced, or released to support, raise or lower a load connected to the cable (or chain).
It would sometimes be desirable to generate a signal corresponding to the position of a supported load, such as to prevent release when the load is raised.
Such devices are typically used in industrial production environments, which are automated to increasing degrees, and load position signals could be used as a part of an automated system.
For example, when transporting the hoist by a trolley moved along an overhead rail, the load may need to be raised to a predetermined height to clear an obstruction prior to being driven to another location. Load position signal generating devices have not been heretofore provided for air balancing hoists.
It is thus an object of the present invention to provide an air balancing hoist incorporating a load position signal generating device.